Balloon occlusion in or on top of the inferior vena cava (IVC) is used today to reduce the venous return to the right heart in order to decrease cardiac output during deployment of stent-grafts in the thoracic aorta (TEVAR). This technique is used to reduce the systolic jet of the left ventricle that may displace the graft when partially opened. Thereby, IVC-occlusion improves accurate and precise deployment of stent-grafts. The sudden increase in resistance in the aorta when a stent-graft is opened may also harm the left-ventricular function. This issue is also improved when the reduction of venous return reduces cardiac output by balloon inflation in or on top of the IVC. In TEVAR, the cardiac output reduction achieved by IVC balloon occlusion is sufficient and easily practiced.
Competing techniques of cardiac output reduction during TEVAR include medically induced temporary cardiac arrest by adenosine and rapid ventricular pacing (“RVP”). RVP is a well-established technique to reduce cardiac output during TEVAR, but carries some significant risks and drawbacks.
The drawbacks of RVP include the short period of time during which RVP is tolerated, so deployment needs to be quick, a cardiologist is frequently needed during the procedure, and there are individual differences in compliance. The risks include that the heart may not return to normal rhythm and consequently require CPR and, that the heart ventricles may fill during the RVP due to the continued venous return and thereby expand the ventricle, which may not handle this high volume. The latter may lead to the need for manual cardiac massage to pump out the left ventricular volume. Overall, this problem decreases the applicability of RVP in hearts with decreased pump-function.
Another field where cardiac output reduction is routinely practiced is in trans-catheter aortic valve implantation (TAVI). Here, RVP is used by most cardiologists and cardiac surgeons. In TAVI, the shortcomings of RVP are more frequent than in TEVAR as patients more frequently have a limited left ventricular myocardial function due to structural and coronary heart disease. Most operators find IVC-balloon occlusion in TAVI not applicable, as it does not completely stop cardiac output due to the continued venous return from the superior vena cava (SVC) and the coronary sinus.
A simultaneous balloon-occlusion of the IVC and the SVC would almost completely stop the venous return to the heart and thereby fast and effectively reduce the cardiac output to near zero. Only venous return from the coronary sinus would be left. In contrast to RVP, this technique will not lead to ventricular expansion and therefore reduce the harmful side-effects of cardiac output reduction by RVP.
This maneuver of simultaneously stopping the IVC and SVC return is routinely used in open cardiac surgery, for instance when a side anastomosis of the ascending aorta is opened, to allow slow and controlled filling and reduce strain on the new anastomosis. However, such procedures are not generally used during minimally-invasive procedures.